Unintended drilling induced fractures are known to increase operating costs and reduce efficiency of well operations. Fractures can cause well instability, well collapse, stuck drill pipes, costly pipe removal and maintenance, and non-productive well downtime. For example, over a typical one-year period, it is estimated that up to one-third of non-productive time can be attributed to lost circulation caused by unintended fracture formations. In addition, the cost of operating a well may increase significantly due to the need to replace drilling fluid and cement lost into the formation. An inability to properly treat and control such fracture formations may result in reservoir damage due to mud losses, and even the possibility of blow-outs due to inadequate hydrostatic pressures downhole.
To mitigate the effects of unintended fracture formations, so-called “lost circulation materials” are often used to seal or obstruct the fracture formations in subterranean reservoirs. Rig operators, for example, commonly use rough estimates of fracture size distributions and “rules of thumb” based on experience to determine the type, amounts and/or combinations of materials to apply to fractures. Such materials include may include cement, crushed walnuts and other synthetic materials that the operator determines to be appropriate for the well based on that operator's experience with the well.
A major shortcoming, however, is that the determination of the materials to be used is done without taking advantage of abstract rock properties and operational data, such as may be derived by reservoir modelers, to more accurately create an optimal concentrations and amounts of the products to be applied. In practice, operational personnel rarely delve into detailed reservoir modeling data, and regardless, have no tools to use such data to determined optimized blends of lost circulation products to be used. In addition, the range of product options and sizes available to operators are typically limited to those products used or manufactured by vendors or service providers supporting the drilling operations.
As such, a need exists to more effectively treat fracture formations in order to lower operational costs and increase drilling efficiency. In particular, a need exists in a planning phase to combine detailed reservoir modeling data with a robust range of lost circulation material product options in order to derive an optimal fill blend for a specific fracture or set of fractures.